ports/sysdeps/arm/armv6t2/ffsll.S

   1 /* ffsll -- find first set bit in a long long, from least significant end.
   2    Copyright (C) 2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20
  21         .syntax unified
  22         .text
  23
  24 ENTRY (ffsll)
  25         @ If low part is 0, operate on the high part.  Ensure that the
  26         @ word on which we operate is in r0.  Set r2 to the bit offset
  27         @ of the word being considered.  Set the flags for the word
  28         @ being operated on.
  29 #ifdef __ARMEL__
  30         cmp     r0, #0
  31         itee    ne
  32         movne   r2, #0
  33         moveq   r2, #32
  34         movseq  r0, r1
  35 #else
  36         cmp     r1, #0
  37         ittee   ne
  38         movne   r2, #0
  39         movne   r0, r1
  40         moveq   r2, #32
  41         cmpeq   r0, #0
  42 #endif
  43         @ Perform the ffs on r0.
  44         rbit    r0, r0
  45         ittt    ne
  46         clzne   r0, r0
  47         addne   r2, r2, #1
  48         addne   r0, r0, r2
  49         bx      lr
  50 END (ffsll)